Clinical characteristics and long-term outcomes of 101 patients with urea cycle disorders in China.

Background: Urea cycle disorders (UCDs) are a group of rare genetic metabolic disorders characterized by hyperammonemia, which can lead to neurological damage, systemic complications, and even death. Understanding UCDs' clinical features and progression in the Chinese population will fill research gaps and benefit patients globally.

Methods: This retrospective study evaluated the clinical, biochemical, genetic characteristics, and long-term outcomes in 101 Chinese patients with six subtypes of UCDs between 2007 and 2024. Data were collected from medical records and analyzed.

Results: The overall survival rate was 93.0% among UCD patients. An equal gender ratio was observed in ornithine transcarbamylase deficiency. Newborn screening (NBS) was conducted in this cohort, and 57.0% of patients were diagnosed through NBS. Neurological and gastrointestinal symptoms were the most common. Symptoms often appeared within the first year, especially in the first month. Arginine was the most frequently used treatment, with glycerol phenylbutyrate often used as a nitrogen scavenger in severe cases. Biochemical analysis showed subtype-specific differences, including notable declines in leucine and glycine on low-protein diets. Genetic analysis revealed a wide distribution of mutations, with few hotspots and 17 newly identified mutations. Clinically diagnosed patients had worse outcomes than those diagnosed via newborn screening.

Conclusion: This study is the first to describe the clinical features and long-term outcomes of UCDs in a large sample of Chinese patients, highlighting the importance of newborn screening for early diagnosis and improved treatment outcomes.